Deformation features and failure mechanism of subsea shield tunnels with different burial depths crossing fault-zone

Abstract

Shield tunneling processes can result in accidents like water inrush and collapse due to instability in the tunnel face. This paper conducts a systematic investigation of the deformation features and failure mechanism of subsea shield tunnels with different burial depths crossing fault zone. The research entails combing theoretical analysis, numerical simulation, and data mining with the second subsea tunnel in Jiaozhou Bay, Qingdao. The impact of the shallow and deep burial depths on the damage modes of the shield tunnel face is analyzed from the perspective of the pressure arch effect. When the tunnel burial depth exceeds the limit, the overlying rock of the tunnel will form a pressure arch that supports the overlying rock. The study investigates the impact of various factors on the tunnel face’s failure modes using a fluid-structure interaction approach. Among them, as the thickness of the overlying bearing stratum increased, the displacement of the tunnel face initially decreased but later increased. The increase of cohesion and internal friction angle contributed to decreasing the displacement of the tunnel face, while seawater depth and tunnel diameter exhibited diverse effects. In the grey correlation analysis, the seawater depth exhibited the most sensitive impact on the pressure arch height.

Keywords:

• Instability
• subsea shield tunnel
• fault zone
• different burial depth
• fluid-structure interaction

Acknowledgments

Research in this paper is supported by the National Natural Science Foundation of China (grant numbers 42293351, 41877239, 51422904, and 51379112), Shandong Provincial Natural Science Foundation (grant number ZR2022QD014), and the Postdoctoral Innovation Project of Shandong Province (SDCX-ZG-202203030).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

National Natural Science Foundation of China; Shandong Provincial Natural Science Foundation; Postdoctoral Innovation Project of Shandong Province.